wildhaber



Sept. 25, 1928. 1,685,441,-

" E. WILDHABER METHOD OF PRODUCING GEARS Filed Feb. 28-, 1927 2 Shuts-Sheet 1 INVENTOR Emmi, Wildizdber Sept. 25, 1928. 1,685,441

' E. WILDHABER IIETHOD OF PRODUCING GEARS I Filed Feb. 28, 19 27 2 Sheets-Sheet 2 r Emwrmzme 6/ .62 I v ATTOR J Patented Sept. 25, 1928.

UNITED STATES PATENT OFFICE.

ERNEST WILDI-IABER, OF ROCHESTER, NEXV YORK, ASSIGNOR TO GLEASON WORKS, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

METHOD OF PRODUCING GEARS.

Application filed February 28, 1927.

The present invention relates to a method of producing bevel gears and particularly to a method of producing gears provided with longitudinally curved teeth.

The primary object of this invention is to provide a method of producing bevel gear pairs of large ratios, in which the tooth surfaces of each member may be out two sides simultaneously without producing bias hearing when the gears run together, and to overcome limitations of my former inventions relating to the same purpose.

A further object of this invention is to provi do a method for cutting bevel gears in which the tooth surfaces of each member may be out two sides simultaneously, in such manner that the teeth taper in depth along their length in proportion to the taper of the gear itself with the tooth bottoms running substantially to the gear apexes, so that the gears are just as strong as gears whose tooth surfaces are cutone side at a time.

A, further object of this invention is to per mit of cutting both members of a pair of bevel gears two sides simultaneously with any de sired spiral angle.

A further object of this invention is to provi de a method for cutting bevel gears whereby the tooth profiles of opposite sides of the teeth may be differently curved by any desirable amount, while cutting two sides simultaneously, so as to get a desirable tooth bearing between the mating gears.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims.

In the accompanying drawings, I have illustrated the preferred method of producing a bevel gear pair according to this invention and one modification thereof. It will be understood, however, that the invention is capable of further modification within its scope and within the limits of the accompanying claims.

in the drawings:

Figure 1 is a plan view, illustrating diagrammatically the preferred method of producing a pinion according to this invention;

Figure 2 is a side elevational view further illustrative of the preferred method of producing the pinion;

Figure 8 is an end elevation showing, some what diagrammatically, the preferred method sented by the tool.

Serial No. 171,607.

of applying the generating roll in producing the pinion;

Figures 4 and 5 are a side elevation and plan View, respectively, illustrating'the preferred method of producing the gear or larger member of the pair with this invention;

Figure 6 is an end view corresponding to Figure 3 and illustrating diagrammatically the manner of rolling the gear and tool relatively to each other to generate the tooth profiles of the gear;

Figure 7 is a side elevational view illustrating a modified method of producing gears with this invention;

Figures 8 and 9 are diz grammatic views further illustrative of the method of producing the gear or larger member of the pair and Figures 10 and 11 are diagrammatic views illustrating how the tooth profile of the gear may be modified by the method disclosed diagrammatically in Figure 8 and 9.

In practicing this invention, the pinion or Smaller member of the pair, is preferably cut in the manner disclosed in my prior copending application No. 89,479, filed February 19, 1926, namely. by using a cutting tool whose pressure angle is greater than the pressure angle of the tooth side to be cut and rotating this tool in engagement with the pinion blank while imparting a relative rolling motion between the tool and blank in which the blank rolls as with a cone larger than its pitch cone on the pitchsurface of the basic gear repre- The gear, or larger member of the pair, is cut, preferably, with a tool, having the same pressure angle as that of the tooth side to be cut on the blank, in a generating operation in which the tool and blank are moved relatively to each other as though the blank were meshing with a basic gear, represented by the tool, whose axis is offset from the axis of the blank. In the generation of the gear, the blank rolls with its pitch surface on the pitch surface of the basic gear, which the tool represents.

Bv producing the two members of a pair in the manner described, it has been found that their tooth surfaces can be out two sides simultaneously and that the gears may be provided with bottoms which run toward their apeXes and that the gears will mesh together without bias hearing. The present invention, hence, provides a method for speeding up the production of bevel gears while, at the same time, p roviding gears which will run together in a most satisfactory manner. 7

This invention is applicable to the production of bevel gears having straight teeth, but is especially suited ior t rutting oi spiral bevel gears, ha is bevel hears .liavinglongitudinally curved teeth. it t i 1 V lVith the present invention itis possihle to cut gear pairs of large ratios practically and with theoretical correctness in a diu ilexi operation, that is, in a method in which the side ,laces ofeach inem'bei are cut two sides simultaneously. The present invention hence,

avoic'ls a limitation bzi'the method of my prior applrcatron mentioned.

The present inven ti'on can .be employed, moreover, "where the tooth number otth'e'erown gear issn'iall, a characteristic practical improvement oi the prior application mentioned "As 'hasth'een pointed out in my prior application 1Y0. 89,475), already referred to, it is possible to cut bevel gears'two sides si'n ultaneously with teeth "of tapering depth and -with tooth bottoms which run fillllSttlIltlttllytt) the apex by en'iploying a cutterwh'ose cutting "edges are of greater 'pressure' angle thatthe tooth surfaces t'o'loecut therebyandby 'rollinh thisci' tte'r and the blank relatively toeach otherasthou'gh a cone larger-than the pitch cone (it tl e blank were rollingon the pitch surface ot thegeai' which the toolrepresents. This method of cutting gears employed, in'eterably, in cutting the 'pinion or'smaller member of pair with the presentinvention. This method of eutting'is illustrated iifl igures1,2and3."

' 12 indicates a cutter which is in the term of a rotary annular face mill and which provided with a plurality of cutting blades 13. The cutting hlades lfii may,eaehot them, have two side finish cutting edges, or may the searranoed' that' alternate blades are provided with cutting edges for finish cutting opposite sides of the teeth. The cutting edi'esoit the tool 12 represents side'tooth surfaces of a basic ay 14 which 'in' 'the' preferred embodiment of this invention is providedwitltteeth1'5 whose side surfaces are portionsot spherical surfaces of 1'evo1utii0n.*'Tlie convex pitch -lines 16 of the teethot the crown gear 14 are arcs 0t circles whose centers meat 17, L7, 17' etc. while the concave pitch lines '18 are arcs of circles whose centers are at 19, i9, 19'. etc. "The centers' 17, 17-,' 17" and 19', 19., 19 etc. all lie on the same circle 20; The conv'ex tooth surfaces, themselves, are parts of convex spherical surfaces"whosesphere centers 21, 21, 21 ci'lie' on a circle 22,"which projects'asa straight line in'Figure 2, whichis situated belowthe pitch plane 230i? the crown gear. The concave tooth surfacesarefliltewise, parts 01 concave s l'ierieal surfaces wl'mserenters"23, 23,"23., eteilie' on a circle 2i: \vlnch is'situia'ted above the pitch plane th n h n of the crown gear. For theoretically correct gearing, the distance a; of the circle 2st above the pitch plane 25 should be the same as the distance 1/ of the circle 22 below that plane. vVith this invention, the pinion or smaller member of the pair, preferably pr laced conjugate to a crown gear, 'sueli as l ,the pressure angles of wlioseto'o'th sides are larger V sure angles of the tooth sides to be produc cl on the pinion.

The crown gear is represented by the tool 12, whose finish cutting edges have pressure angles larger than the pressure angles o l ithe tooth sides to be cut thereby. The pressure angle of a cutting edge, ashere understood, is equal to half the angl e'included between opposite side finish cutting edges.

a To produce two side faces of the pinion blank :26 simultaneously and conjugate to the crown gear .1 l,the tool 12 mustabeso positionedthatits axis 28 passesthrough the center 21 of a convex sphericaltooth sur'taceof the crown gear and alsothrough thecenter ot a concave sphericaltooth surftace oi the crown gear. Tnotlrerwords, the outside and inside finish cutting edges off ',the blades 12 of the tool must be'respectively, portions of convex and concave spherical surtaces whose centers 21and23rai'ezlocated onthe tool axis V 28 and which arc'of the same radius, respectively, are the convex and concave tooth sides 16 and 18 respectively, ol the croyvngear teeth 15.

The tooth surfaces of the pinion are generated by rolling the hlankwith a surfiace other than its pitch surface, and pre tera'bly'of greater dimension than its pitch surface, on the pitch surface of the basic gear which the tool IGPI'QSQIlt-S. This method is different from that ordinarily 'eniployed in generating bevel gears, forbevel gears 'are ordinarily generated in a rolling operation in which the pitch surface oi the blank iolls'on the pitch surface of the basic gear which the toolrepresents. I

The-tool 12, then is rotated on its axis in engagement with the pinionfblank 26 and the blank and tool are rolled relativelyito each other as though a conical surfaeei-EO offthe blank, whose cone angle 3.1 is gre'aterthan the pitch coneanogle 32 of the ,blanlgwer rolling on the pitch surface 25 or the'crown gear is ivl rich the tool represents. In the rolling n10 tien, the .hlanlc 2G 'i's'rotated onits axis'33 and simultaneously"an additional relative n'iovement is imparted between the tool and' blank ahoutrn axis 34 representing the axis of the crown 'ear lt l'and intersecting the blank axis 33 in the .hlank 'apex 35. i

' In the niannerdescribed, two tooth surfaces otthe pinionbl'ank 26are cut'simultaneously. The blank is then indexed and the operation proceeds as before.

The gear. or larger member of the pair, is rut in a different kindo't'operationriii'which the tool represents a crown gear whose axis is offset from the axis of the blank. This is again different from the usual methods of generating bevel gears, since, ordinarily, the blank is rolled as on a crown gear or basic gear whose axis intersects the blank axis in its apex.

The tool for cutting the gear is shown at 40. It provided with cutting blades 41. whose side finish cutting edges are of spherical profile, representing side tooth surfacis of the crown gear 42, with which the gear blank 43 is rolled during generation. The pressure angles of both inside and outside finish cutting edges of the tool are the same the pressure angles of the tooth surfaces of the gear blank 43 to be cut hereby. The outside finish cutting edges of the blade 4]. are portions of a convex spherical surface whose center is at 44 on the axis 45 of the tool, while the inside finish cutting edges of the blades 41 are portions of a concave spherical surface whose center is at 46 upon the axis 45 of the tool. The tool thus represents a pair of adjacent ride tooth surfaces of the crown gear 42 whose centers are at 44 and 46 respectively. Preferably, the sphere radius of the outside finish cutting edges of the tool 40 is the same as the sphere radius of the inside cutting edges of the tool 12, while the sphere radius of the inside cutting edges of the tool 40 is the same as the sphere radius of the outside cutting edges of the tool 12. The tool 12, will, accordiugly, be smaller in diameter than the tool 4.0. If no mismatch is desired, the sphere radii of outside and inside cutting edges will be made equal.

In the generation of the gear, the tool 40 is rotated on its axis 45 in engagement with the blank 43, while a relative rolling movement is imparted between the tool 40 and blank 43 as though the blank 43 were rolling with its pitch surface 48 on the pitch plane 49 of the crown gear 42 whose axis 50 is offset from, that is, non-intersecting and non-parallel to, the axis 51 of the blank 43. In this rolling movement, the blank 51 is rotated on its axis and the tool and blank moved rela tively to each other about the axis 50 of the crown gear. After two tooth sides of the blank 43 have been cut, the tool and blank are withdrawn relatively to each other and the blank indexed.

A gear 43 and a pinion 26 cut in the manner described will mesh together with their axes 51. and 33 angularly disposed and intersecting and with their apexes and 52 coinciding, as do bevel gears cut accordin to other methods. and they will. transmit true uniform inotion.

The manner in which the an'iount of offset between the crown gear axis 50 and the blank axis 51 is determined will be described below, referr ng particularly to Figures 8 and 9. These figures are diagran'nnatic views, in plan,

of the pitch plane of the crown gear 42. The crown gear apex or center is indicated at 53. The blank is assumed to be so in mesh with the crown gear that its projects into the line 51. 55 and 56 are pitch line elements of ()PPOSliiU side faces of a tooth of the crown gear or a tooth space of the gear 43 generated conjugate thereto. The sphere centers of the tooth sides having the pitch line elements 55 and 56 are at 44 and 46 respe .tively on the projected cutter xis 4?. P indicates a mean point of contact between the crown gear teeth and the tooth space of the gear 43. lVhcn the crown gear and gear have rolled together far enough so that contact between the two takes place at the point P the sphere center 46 will have moved to C which is, accordingly, the center of the spherical tooth surface of the crown gear when tooth contact takes place at P.

The line of contact between the tooth surfaces of the gear and crown gear at any considercd moment, depends on the relative path of the sphere center C with respect to the blank. More accurately speaking, the loca tion of said line of contact (lGPQlKlS solely upon the location of the tangent to said relative path, at the considm'ed instai'it.

This tangent or the direction of relative motion, remains the same, whether the basic tooth surface whose center is at C is turned about 52 or about any other axis 50 or 50 as long as such axis is located on the line 57 connecting the apex 52 of the blank with the center C of tooth curvature, and as long as the turning motion about axis 50 or 50 is such as to move center 0 to the same infinitely close position C. as does a turning motion about In other words. if the distance from the blank apex 52 to the center C is equal to R and the distance from blank apex 52 to the crown gear axis 50 is equal. to as (dis tance 52-50= K) the angle of rotation about axis 00 and the angle of rotation. about the apex o2 are in the following relation lVe may use, therefore, the. basic gear for producing the larger member of the pair, any crown gear having a center 53 or 53 located on the line 5'? and still obtain the same lines of contact between the teeth of the crown gear and gear being cut at the central position P, as would be obtained were the gear rolled on a basic crown gear whose axis intersects the blank axis in the blank apex 52.

ll hile the lines of contact between the gear and crown gear remain the same, regardless of the position of the crown gear center on the line 57, generally speaking, the tooth curvatures do not. The tooth curvature of the ir teeth affected bv the location of the tire n gear center on the line 57.

This will be clear from Figures 9, 10 and 11. When the center (I of tooth curvature is turned about an axis which is oli'set r'rom the'blank apex 52, instead of being turned about an axis which intersects the blank axis, as the usual practise in cutting bevel gears, the ceuterC will. ruoveto C instead of to C, and ii the turning angles 4) and. it, are in the relation given above, the center of tooth curvature, as a result of the present method of cutting, will be displaced, as compared with priormethods, by a distance (Z in a direction parallel to the line T he crown gear tooth profile wlll also be displaced by the same amount (Z indicated in. dotted lines at 59,

over the position 58 which it would occupy, were the axis of the crown gear intersecting the of the blank in its apex 52.

In Figure 10, the circumferential tooth profiles 60 and (ll of a gear and crown gear are shown, when Contact takes place between these two tooth profiles at the mean contact point P. '1" represents the curvature radius of the gear profile and r designates the curvature radius of the crown gear tooth profile, that is, the curvature radius of the cutter. For the mean contact position P, the relative position of the gear and crown gear tooth profiles will be the same, whether the axis of the crown gear intersects the axis of the blank in its apex or whether the axis of the crown gear be oltset from the axis of the blank, as is the casein cutting the larger member of the pair according to the present invention.

In Figure 1 1, the heavy lines 60 and 61 indicate the position of gear and crown gear tooth profiles, when the crown gear axis intersects the axis of the blank, after they have rolled from the position P to a position where contact between these profiles takes place at the point Q. The distances PQ. and PQ, are of the same length on the two profiles 60 and 61, because in the immediate vicinity of the pitch surface, that is, in the immediate vicinity of the point P the profiles of bevel gears roll without sliding. As has been explained, however, the profile of an offset crown gear will not have the same position, after some rolling movement has taken place, as has the profile of a crown gear whose axis intersects the axis of the blank in its apex. On the contrary, the profile oi the tooth oi an offset crown gear will be advanced or withdrawn compared to the position which the profile of a crown gear, having an intersecting axis, would occupy, de fiendingon the tooth side under consideration. An advanced position (52 ot' the tooth profile shown in Figure 11. As a result of the displacement of the tooth profile of the crown gear teeth over the position it would occupy were the crown gear axis intersecting the axis ot the blank, the crown gear tooth profile 62, which is represented by the cutting blade oithe tool, will envelop or sweep out a profile 6?) on the gear being cut, whose curvature radius r is different from r. In the position shown in Fig- .ure 11, actual contact will takeplace between the gear tooth and the cutting -tool,.cro.wn

case were the axis otthe crown gear intersecting the axis of the blank. As the .prolileot the crown gear tooth, namely, the cutter, and its radius a is predetermined, the profile oil the gear tooth will be modified over that which would beproduced with the usual heretotore practised method of cutting ibevel gears. The new gear tooth profile will pass simultaneously through S andP. By varying the positions of the crown gear center -5O along the line 57, therefore, it is possible to change or modiiythe tooth profilecurvature of the gear teeth being cut. "llhe amount of modification which it is possible .to'obtain from different positions or the crown gear center or apex, can be calculated from the known methods of descriptive geometry.

Figures 10 and '11 refer to only one tooth profile of the gear. The tooth .profile oi? the opposite side of the gear tooth will be less curved when the blank is cut in agenerating operation in which the crown gear axis is oil'- set from the axis of theblank, than when derived from a basic :crown gear whose axis passes through the blank apex, inasmuch as "the cutting surface of the otlsetcrown gear is advanced for one tooth sideand Withdrawn for the other tooth side over the position it would occupy when the axis of the crown gear passes through therblank apex.

*In Figure 11 the tool profile (crown gear tooth profile) which is advanced over the usual position, is shown convex for convenience. Ordinarily, in cutting the gear according :to this invention, the concave profile of the spherical cutter will be advanced while the convex profile will recede.

The correction obtained by curving one side of the teeth of the gear more and the other side less than with previousmethods of cutting is desirable because the pin-ion is produced with a tool of increased pressure angle. WVith a pinion produced in this way, the profile curvature of the pinion teeth will be somewhat too large on one side and somewhat too small on the other side, generally. '1. he method of producing the gears described herein permits of compensating for this characteristic of the pinion teeth.

With the present invention, it is preferable but not necessary to employ a true crown gear as the basic element from which the tooth profiles are to be generated. The tool and blank may be rolled relatively to each other as though the blank Were rolling upon the pitch surface of a nominal crown gear, that is, a crown gear whose top surface is a plane and whose pitch surface is a cone. The basic member, which the tool represents, may be. in fact, any suitable form of basic gear.

In Figure 7 the tool 70 is shown in position all to represent a. nominal crown gear whose axis is at 71 and whose pitch surface is indicated at T2. The axis 73 of the tool is here arranged parallel to the axis 71 of the crown gear. in the case of a pinion blank, as before, the blades of the tool will be of increased pressure angle and the blank will roll upon some surface outside its pitch surface. The cutting of a pinion conjugate to a nominal crown gear illustrated in Figure 7. The mating gear may be cut conjugate to a nominal crown gear also, but preferably will be cut, as before, conjugate to a true crown gear.

lVhile the present invention has been described particularly with reference to tools having cutting edges of circular arc profile, representing spherical tooth surfaces of a basic gear, it will be understood that the tools may be of any other suitable profile, also, as straight sided.

.Vhile it is preferred to use the method, herein disclosed, of cutting a gear in conjune tion with the method of cutting a pinion described in my application No. 89,479 and shown in Figures 1, 2 and 3 of the present application, it is also possible to cut both mem bers of a pair of bevel gears, two tooth sides simultaneously, where both members are cut from offset crown gears according to the principles shown in Figures 4, 5, 6 and 8 to 11 inelusive.

While I have illustrated certain preferred embodiments of my invention, it will be undcrstood that this invention is capable of further modification within the limits of the disclosure and the scope of the appended claims and that this application is intended to cover any variations, uses, or adaptations of my invention, following, in general, the principics of the invention and including such departnres from the present disclosure as come within known or customary practice in the art and as may be applied to the essential features hereinbefore set forth and as fall within the limits of the accompanying claims.

Having thus described my invention, what I claim is:

l. The method of producing a pair of bevel gears which consists in generating the side tooth surfaces of one member of the pair two sides simultaneously, by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank. while imparting a relative rolling movement between said cutting edges and the blank in the manner of a gear rolling on a crown gear whose axis intersects the axis of the blank in its apex, and generating the side tooth surfaces of the other member two sides simultaneously by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank while imparting a relative rolling movement between said tools and blank in the manner of a gear meshing with a crown gear, whose axis is offset from the blank axis.

2. The method of producing a pair of bevel gears which consists in generating the side tooth surfaces of one member of the pair two sides sin'iultaneously, by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank while rotating the blank on its axis and simultaneously imparting an additional relative movement between the cutting edges and blank about an axis intersecting the blank axis in its apex, and in generating the side tooth surfaces of the other member of the pair two sides simultaneously by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank while rotating the blank on its axis and simultaneously impart-ing an additional relative movement between the cutting edges and blank about an axis offset from the blank axis.

3. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair by moving a cutting edge, having a pressure angle the same as the pressure angle of the tooth side to be cut thereby, across the face of a tapered gear blank while imparting a relative generating movement between the cutting edge and blank in which the cutting edge and blank are moved relatively to each other in the manner of a gear moving with its pitch surface on'the pitchv surface of a crown gear whose axis is offset from the axis of the blank, and in cutting the side tooth surfaces of the other member of the pair by moving a cutting edge, having a pressure angle greater than the pressure angle of the tooth side to be cut thereby, across the face of a tapered gear blank while imparting a relative rolling movement between said latter cutting edge and blank as though a cone of greater dimension than the pitch cone of the blank were rolling on the pitch surface of a crown gear, whose axis intersects the axis of the blank in its apex.

4. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair by moving a cutting edge, having a pressure angle the same as the p essure angle of the tooth side to be cut thereby, in a curved path across the face of a tapered gear blank while imparting a relative movement between said cutting edge and blank in the manner of a gear moving with its pitch surface on the pitch surface of a crown gear whose axis is offset from the axis of the blank, and in cutting the side tooth surfaces of the other member of the pair by moving a cutting edge, having a pressure angle greater than the pressure angle of the tooth side to be cut thereby, in a curved path across the face of a tapered gear blank while imparting a relative rolling movement be tween-said'latter cutting-edge andblank as though a cone of greater dimensionthan the pitch cone of the blank were rolling on the pitch surface of a crown gear whose axis tapered gear-blank while impartingn relative rolling movement between the cuttlng edge and bhmk in the manner ot a cone of greaterilimension; thanethe pitch cone of theblan-k rolling .on =the pitch surface of a basic gear ren'esentedby the tool, andin cuttinggthe side tooth surfacesofthe other-men'rber of the pairiby' moving: a cuttingedge across the face at a tapcrec blankwhile in'ipartinga relative moven-ient' between the cutting edge amlblankj in the manner of-agear meshing with aibasic gear, represented-by the lattercutting.edge,: whose axisisoiiset from the ixis-of the blank.

3. The method of prodi-icing a pair of bevel' gears'which consists in cutting the sidetooth surfaces ofionemember ofthe pair by mov ing'a icutting edge whose pressure angle is iter than the pressure angle of'the tooth sideto be cut thereby in a-curved path across the face of a tapered gear blank- Whileimp arti n g :a relative rolling movement between the cutting; edge and blankin the manner of a eone of greater dimension than the-pitch cone of the blankrollingon'the pitch -sur face of abasic gear represented by ithe cutting edge and in cuttingsthe side tooth surfacesof the otber:member' of the pair byimoving a cutting edge ina curved path acrossthe face of a-tapered gear blank while imparting a relative movement between the latter cutting edge and blank in the manner of a gear meshing; with a basic gear, represented by thecuttmg edge, whose axis is offset from the blank axis.

7. The method of producing a pair-of bevel gears which consists-in cutting the side tooth surfaces of one member of the pair bymoving a cuttingnedge, having a pressure angle the same as'theprcssure angle of the tooth sideto be cut thereby, acrossthe'face of a tapered :gear blank i while imparting a relativemovcment betwecn the cutting edge andblank-as though the blank were movingwith its'pitehi cone on the'pitchsurface of 'a basic gear, represented by the tool, whose axis is offset from the axis of the blank, and in cutting the sidetooth surfaces of the other memberof the 'pair by moving a cutting edge, whose pressure angle is greater than the pressure angle of the tooth to be cut thereby, across the face of a tapered gear blank 'while impartinga relative rolling movement between the latter cutting edge and blank as SHlO tO 'be cut th-cre-by,'-across the face ofa though a cone ofgreaterdimension thanthe pitch cone of the blank were rolling on the pitch surface of a basic gear, represented by the latter cutting edge, Whose axis intersects the blank axisinits apex.

8. The method'ofproducing a pair of bevel gears, which consists in'cutting-the side tooth surfaces of-one member ofthe pair by moving abutting edge, having a-pressure angle the same as the pressure angle ofthe toothside to be cut thereby,;i11=a curved path across the face ofa tapered gear blank while impartii'lg a relative movement between, the cutting edge-"and blank as though the blank were moving with its piteh cone onthe pitch surfaeecf a basic gear, represented by the cutting edge, whose axi sis offset from the axis-of the blank, and in cutting the side tooth surfaces of the othermember'of the'pairby: moving a cutting edge, having a pressure angle greater than the pressure angle of the tooth sideto' be cut thereby in a; curved "path across the face of 'a'tapered gear blank while impart ing a relative l'OlllDgJl-l-OVBIDGHE betwcen'the latter cuttingvedge and bl'ankas though a'coneof greater di mension th an the pitch cone of the blank were rollingOnthe'pitch'surface of a basic gear, represented by; the latter cutting edge,whose axis intersects'the blank axis'in its apex: a

9. The method of producing a pair of bevel gears; which consists in cutting the side tooth surfaces of one member of the'pairtwo sides sin'iultaneously by movingapair of'cuttin-g edges, havingpressure angles'equal to the pressureanglesof the tooth surfaces to be cut thereby, across thefa-ce'ofa tapered gear blank While imparting arelativemovement between the cutting edges a-nd blank in the manner of a gear'n'ieshingiwith a basic gear, represented byth'e cutting edges, WhOSG'flXiS is o'ifset from the axis of-the blank, andin cutting-wthe side tooth surfaces of'the other member of the pair two sidessimultaneously by movingtapair of cutting edg'es, whose pressure angles are greater than the pressure angles-of thetooth sides tobecut thereby, across the face of a tapered gear blank while imparting a relative rolling movement between the latter cutting: edges *and blank inthe manner of a con'e'of greater dimension than 'the pitch cone of theblankrolling-on the pitchsurfaceof a basic gear, represented by the latter cut ing edges, whose axis inter sects the axis of the 'blankinits apex.

10. Themetho'd of producing a pair 'of bevel gears which consists in cutting theside tooth surfaces of one member of the pair twosides simultaneously by moving a pair of cutting edges, having pressure anglesequal to the pressure-angles ofthetooth surfaces to be cut thereby, in concentrically curved paths acrossthe face of a tapered gear blank while in'ipartin'g a relative movement'between the cutting edges and blank in the manner of a Ian gear moving with. its pitch surface on the pitch surface of a basic gear, represented by the cutting edges, whose axis is offset from the axis of the blank, and in cutting the side tooth surfaces of the other member of the pair two sides siimjiltaneously by moving a pair of cutting edges, having pressure angles greater than the pressure angles of the tooth sides to be cut tllGIGlDf-f, in concentrically curved paths across the face of a ta 3G1'Od gear blank while imparting a relative rolling movement between the latter cutting edges and blank in the manner. of a cone of greater dimension than the pitch cone of the blank rolling on the pitch surface of a basic gear, represented by the latter cutting edges, whose axis intersects the axis of the blank in its apex.

11. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair two sides simultaneously by moving a pair of cutting edges, whose pressure angles are greaterthan the pressure angles of the tooth sides to be cut thereby, across the face of a tapered gear blank while imparting a relative rolling movement between, the cutting edges and blank in the manner of a cone of greater dimension than the pitch cone of the blank rolling on the pitch surface of a basic gear, represented by the cutting edges, and in cutting the side tooth surfaces of the other member of the pair two sides simultaneously by moving a pair of cutting edges across the face of a tapered gear blank while imparting a relative roiling movement between the latter cutting edges and blank in the manner of gear meshing with a basic gear, represented by the latter cutting edges, whose axis is offset from the blank axis.

12. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair two sides simultaneously by moving a pair of cut ting edges, having pressure angles greater I than the pressure angles of the tooth sides to be cut thereby, in concentrically curved paths across the face of a tapered gear blank while innarting a relative rolling movement between the cutting edges and blank in the manner of a cone of greater dimension than the pitch cone of the blank rolling on the pitch surface of a basic gear, represented by the cutting edges, and in cutting the side tooth surfaces of the other member of the pair, by moving av pair of cutting edges in concentrically curved paths across the ace of a tapered blank while imparting a relative move ment between the cutting edges and blank in the manner of a gear meshing with a basic gear, represented by the latter cutting edges, whose axis is offset from the blank axis.

13. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair two sides simultaneously by selecting a rotary annular face mill, provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, rotating the tool in en gagement with a tapered gear blank to out two side faces of the blank simultaneously and simultaneously imparting a relative movement between the tool and blank in the manner of a gear meshing with a basic gear, represented by the tool, whose axis offset from the axis of the blank and in cutting the side tooth surfaces of the other member of the pair two sides simultaneously by selecting a rotary annular face mill, provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, rotating said tool in engagement with a tapered gear blank and simultaneously imparting a relative rolling movement between the latter tool and blank in the manner of a gear rolling with a basic gear, represented by the latter tool, whose axis intersects the blank axis in its apex.

14;. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one men'iber of the pair two sides simultaneously by selecting a rotary annular face mill, provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, rotating said tool in engagementwith a tapered ear blank and simultaneously imparting a relative movement between the tool and blank in the manner of a gear movin with its pitch cone on the pitch surface of a asic gear, represented by the tool, whose axis is offset from the axis of the blank, and in cutting the side tooth surfaces of the other member of the pair two sides sin'mltaneously by selecting a rotary annularface mill, provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, said edges having pressure angle-s greater than the pressure angles of the tooth sides to be cut thereby, rotating the latter tool in engagement with a tapered gear blank and si multaneously imparting a relative rolling movement between the latter tool and blank as though a cone of greater dimension than the pitch cone of the blank were rolling on the pitch surface of a basic gear, represented by L110 latter tool, whose axis intersects the blank axis in its apex.

15. The method of producing a bevel gear conjugate to a basic crown gear having longitudinally curved teeth which consists in moving a tool across the face of a tapered gear blank in a path curved about a fixed center, representing a center of tooth curvature of the teeth of the crown gear, while in'ipartin g a relative rolling movement between the tool and blank in the manner of a gear rolling with the basic crown gear, in which the axis of the blank is offset from the axis of the crown gear, and the center of the crown gear longitudinally about the lieson a line, ,in the pitch plane of the crown tween the tool. and blank inf the nian ier a cone of greater dimension than the pitchc one; of the blank rolling on the pitch surface of a basic gear, represented by the toohwhose axis intersects the axis of theblank in its apex, and in cutting the side tooth surfaces: of the other member of the pairtwo sides gear, connecting the ape icolf the blank and thecenter ottooth curvature. I y y p I 1(3. The method of producing a bevel gear conjugate to a basic crown gearhaving teeth, the adj agent side faces, of which are arranged in pairs curved longitudinally about the same center, whicheons sin movinga pair of cutting edges across the face of a tapereil gear blank in paths curvedlongitudinally about the same center to out two side facesot the blank siniultaneously,wl ile in parting a relative rolling n oyen ent between the cutting edgz es and blank in the manner ()Ill a gear rolling with thebasiccrmvugear, in, which the asis of the blank otlj'set from the axis of the crown gear andthe center thecrown gear lies on a line, in the pitch surface of the crown gear, cennecting the apex of the blank and the center of tooth curvatureh I l 17. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one memliier of the pair vtwo sides simultaneously by moving pair of cutting edges, having pressure angles greater than'the pressure anglesl'ot the tooth sides to cut thereby, in concentrically curved paths across the face of atapered gear blank while imparting a relative rollingmovement between the cutting edges and blank in the manner of a cone oi. greater dimension than the pitch'cone of the blank rolling on the pitchsuriiace of a basic gear repr ented by thecuttiug edges, whosea s intersects the axis otthe blank in its apex, andin cutting the side tooth sur taces otthe otliei."n1eniber ot the pair conjugate to basic having longitudinally curved teethwhose side tooth surfaces are, arranged in pairs curved n e center, moving apair oti cutting edges inconcentrically curved paths acrossthe face of ata; peretl gear blank while imparting a relative movement between the latter cutting edges and blank in themanner a geaifl ii esliing with the basic gear, represented by the cut ting edges, while maintaining the aiiis oli the blankotliset from the axis oi said basic gear and the apex of said basic gear on a line, in the pitch sur'lace of the basic gear, connecting the apex of the blank and the center of tooth curvature of the basic gear.

18. The method o't producing a pair of bevel gearswhich consists in cutting the side tooth surfaces of one member of the pair two sides simultaneously by employing an annular iacemill, having cutting edges, adapt ed, to cut opposite side tooth faces ot the blank, whose pressure angles are greater than the pressure angles of the side tooth faces tobe cut thereby, and rotating said tool in engagement with a tapered blank while imparting a relative rolling movement besiu'uiltaneously so as to, be conjugate to a basic gear having teeth, the adjacent si'de laces oi which are arranged inpairsjc'urve d li mgitiidinally about, the same center by 50- tat' :liaces ot the blank in en asement with a'ta V I 7 1 5 1' i v pered gear blank Wll'llO in'iparting a relat ve movement between the latter tool and blank in tlie manner of a gear' ineshingwith said,

latter basic gear, while maintaining the axis ot the blank oil'set from the aims ofth'e basic 7 iC; -i1; gear and the center of the basic gear on a line,

inthe pitch surfac'eot the basic gear, connesting the apex'of the bla'nkwith the center of tooth curvature o'l 'the' ba'si'c gear 19. The method of producing a p berelgears which" consists ineuttingjt tooth"surjlaeesjoli one member otthe pa r all" y cutting edges, of circulararelprofi'lef and havin g greater pressure angles than thellpressure angles of the tooth faces to be cut'the'reby, in separate concentrically curved paths a'crjoss the taco of a tapered geaii' blank whileim'parb i a relative rolling motion between the cutt ed and blank as though a" cone of and iii cutting the sidetooth rtaces ofj the other member of'the palr two sides simultaneously by employing a pa r" of cuttnig edges,o'i circular arc profile whose'radiiare such that the ci itting edge whichicutsj one side surit'ace'of thelblank has thefsaii'i'eradius as the cutting edge which cuts'th'e mating" ie s tooth surface of theffirst 'gear, an said cutting edges n separateconcentr cally curved paths across the face ata'pef eclfg'ear blank while imparting a relativemhvenientj betu :en the latter cutting edges and blank in the inanner'ot a gear meshing with 'a'crown gear whose aiiis is ojl'l'set from the aKis of the blank. I V i 4 20. lhe method of producing afpair of bevel gears which consists in cutti'ngtl side tooth surfaces of one men'iber o'f the pair two 'ug an aunular :tac'e' mill, having cutting ar'iapted to (IHifOPPOSliLG suletooth qsidi e'i sides simultaneously by moving a pa '1 of A ter tlimension than the pitch cone ofthe blank were rollii g on' thepitch surface ofthe' basic geari.'epresented by the cutting edges,

blank as though a cone of greater dimension than the pitch cone of the blank were rolling on the pitch surface of a basic gear, represented by the tool, who e intersects the axis the blank in its ape and in cutting the side tooth Slll'ftiOS of c other member of the pair two sides simultaneously by employing a rotary annular face mill, having cutting edges circular arc prolile whose pressure angles are the same as the pressure angles of the tooth faces to be cut thereby and whose radii are such that the cutting edge which cuts one side surface of the blank has the same radius the ci'itting edge of the first named tool, which cuts the matin tooth surface of the first gear, and rotating said tool in. engagement with a tapered gear blank while imparting a relative movement between the tool and blank in the manner gear n'ieshing with basic gear, represent l by the tool, whose axis is orl'setfrom the aXi s of the blank.

21. The method of producing a pair of bevel gears, which. consists in cut ng the side tooth surfaces of one men'iber of the pair two sides simultaneously by moving pair of cutting edges in concentric curved paths across the face of a tapered blank, while imparting a relative gencratin; movement between the cutting edges and blank, as though the blank were meshing with a basic gear represented by the cutting edges, and in cutting the side tooth surfaces of the other member of the pair two sides simultaneously by moving a pair of cutting edges, liswinrr pressure angles different from the pressure angles of the first pair of cutting edges, in concentric curved paths across the face of a tapered gear blank while iniparting a rela tive generating movement between the latter cutting edges and blank, as though the blank were meshing with a basic gear represented by said cutting edges.

22. The method of producing a pair of bevel gears which consists in generating the side tooth surfaces of one member of the pair two sides simultaneously, by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank while rotat ngthe blank on axis and simnltancously imparting an additional re|ative movement between the cuttin edges and. blank about an axis intersecting the blank axis in its apex, and in generating the side tooth surfaces of the other member of the pair two sides simultaneously by moving a pair of cutting edges. having pressure angles different from the pressure angles of the Fi st pair of cutting edges, in concentric curved paths across the face of a tapered blank while rotating the blank on its 2718 and simnltaneously impartin an additional relative movem nt between the latter cutting and blank about axis oifsct from ink axis.

23. The method of producing a pair of bevel gears which consists in generating the side tooth surfaces of one member of the pair two sides simultaneously by moving a pair of cutting edges in concentric curved paths across the face of a tapered gear blank while imparting a relative rolling movement between the cuttingedges and blank in the manner of a gear meshing with a basic crown gear whose axis intersects the blank axis in its apex, and in generating the side tooth surfaces the other member of the pair two sices simultaneously by moving a pair of cuttingedges, having pressure angles dill'ercnt from the pressure angles of the first pair of cutting edges, in concentric curved paths across the face of a tapered gear blank while imparting a relative movement between the latter cu ting edges and blank corresponding to that of a gear meshing with a basic crown gear whose axis is offset from the axis of the blank.

Bl. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair with a rotary annular face mill provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, while rotating said tool in cngz cement with a tapered gear blank and impariing a relative generating movement between the tool and blank as though the blank were meshing with a basic gear l'tlJl'OSQlli'ECl by the tool and in cutting the side tooth faces of the other member of the pair with a rotary annular face mill having a different dian'ieter from the first tool by retating the latter tool in engagement with a tapered gea r blank while imparting a relative generating movement between the latter tool and blank as though the blank were meshing with a basic gear represented by the latter tool.

25. The method of producing a pair of bevel gears which consists in cutting the side tooth surfaces of one member of the pair with a rotary annular face mill, provided with cutting edges adapted to finish cut opposite de tooth faces of the blank, by rotating said tool in engagement with the blank while imparting a relative generating movement between the tool and blank as though the blank. were meshing with a basic gear represented by the tool, and in cutting the side tooth faces of the other member of the pair with a rotary annular face mill, provieed with cutting edges adapted to finish cut opposite side tooth faces of the blank whose diameter is different from the d ameter of the first tool, by rotating the latter tool in engagement with the taper gear blank while imparting a relative generating movement between the latter tool d blank as though the blank were rolling with a basic gear represented by the latter tool it The method of prodl Kill titi

bevel gun's which consists in cutting the side tooth surfaces oi one member of the pair with a rota annular tare mill, provided with cut ting; ed es lapted to finish cut opposite side tooth t'aces ot the blank, by rotating said tool in enega enient with a taper gear blank while inipni ting); relative gene 'ating movement between the tool and blank 2 though the blank. were meshing: with a basic gear represented by the tool, and in cutting the side tooth faces of the other iuelnb'er oi' the pair with a rotaiy annular iiace mill, having a 'ditte'rcnt oialneter from the first tool, by rotating: the latter tool in engagement with a tapered gear bla while inuiaiitii'm; a relative ggeneratin g iTHFVOii'Hili' between the latter tool and blank as though the blank were meshing; with a basic gear rein'esented by the latter tool, the axis oi the blank, during generation (it one member o l the pair. being: maintained otl'set from the axis of the basic gear to which it is beinggenerated conjugate.

27. The method of nfoducing; a pair ol bevel gears which consists in cutting the side tooth surfaces of one member 0'; the pair with a rotary annular taco mill, provided with cutting; edges adapted to cut opposite side tooth fates of the blank, by rotatingsaid tool in engagement with a tapered gear blank while in'ipartingr a relative generating movement between the tool and blank corresponding to that of a gear moshing with a basic gear represented. by the tool, and in cutting; the side tooth SHT'EMOS oil. the other member of the pair with a rotary annular face mill, provided with cutting; edges adapted to finish cut opposite side tooth faces of the blank, whose diameter is ditierent 'lirom the diameter of the first tool, by rotating the latter tool in engagement with a tapered gear blank while iinpz'irting a relative ,e'eneratin 3, movement between the latter tool and blank -as tl'ione'h the blank were meshing with a basic gear represented by the latter tool, the

was of the blank, durin 'eneration of one member of the pair, being n'iaintained olij'sct from the axis of the basic gear to which it is generated conjugate.

28. The method oi producing a pair of bevel nears which consists in cutting the side tooth surtares of one member of the pair with a rotary annular tare mill, provided with cutting edges adapted to finish cut opposite side tooth faces of the blank, by'ij'otating; the latter tool in engagementwith a tapered gear blank while iu'ipartiinr a relative generating movement between the tool and blank as though the blank were meshing with a basic crown gear, represented by the tool, whose a?! intersects the astis ot the blank in its "and in. cutting the side tooth surfaces up r V ot the other n'ieinher of the pair with a rotary annular tare mill, provided with cutting edges adapted to finish cut opposite side tooth Faces of the blank, whose diameter is diilerent from the di amcter or the first named tool, by rotating the latter tool in engagement with a tapered gear blank while imparting a relative generating movement between the latt r tool and blunt: as though the blank were meshing with a basic gear represented by the latter tool, whose axis is o'llset from the axis oti'he blank.

29. The method of producing a pair of bevel gears which consists in cutting; the side tooth surfaces of one member of ti e pair two sides sinuiltaneously by moving a pair of cutting; edges, oi circular arc protilc, in separate concentri :ally curved paths across the face of a tapered gear blank while imparting a. relative geueratii'ig movement between, the (wilting edges and bla ;k as though the blank were meshii with a basic ,e'ear represented by said cutting edges and in cutting the side tooth faces of the other nien'rher of the pair two sides sinuiltaneously with a pair of cutting edges, of circular arc profile, whose pressure angles are ditl'erentfrom the pressure angles ot the first pair ot cutting edges, by movlog the latter cutting edges in separate c0ncentrieally curved paths across the taco 0t a tapered gear blank while imparting a rclative generating movement between thevlatter cutting edges an d blank as though the blank were meshing with a basic gear represented by the latter cutting edges.

S0. The method of producing a pair of bevcl nears which consists in cutting'therside tooth faces of one member of the pair two sides simultaneously by moving a pair of cut ting edges, of circular arc profile, in separate concentrically curved paths across the face of a tapered gear blank while imparting a relative generating"movement between said cutting edges and blankas though the blank were meshing with a basic gear represented by said cutting' edges, and in cutting; the side tooth faces of the other member of the pair two sides simi'iltaneously with a pair of cutting edges, of circular arc profile whose pressure angles are ditl'erent from the pressure angles of the first pair of cutting edges, by moving the latter cutting edges in separate concentrically curved paths across the face of a tapered gear blank while imparting a relative generating movement between the latter cutting edges and blank in the manner of a .gear meslin'ip; with a basic gear, represented by the latter cutting edges, whose axis is offset from the axis ot'fthe blank.

31. The method of producing a pair of bevel gears which consists in cutting thcside tooth surfaces of one naen'lber ot the pair two sides simultaneously with a rotary annular face mill, having cutting; edges ot circular arc profile which are adapted to cut opposite side tooth fac 38 of the blank, by rotatin said tool in engagement with a tapered gear blank while imparting; a relative genera 'na movement between. the tool and blunt: as though the blank were meshing with a basic gear, represented by the tool, and in cutting the side tooth faces of the other member of the pair two sides simultaneously with a rotary annular face mill, having cutting edges of circular are profile which are adapted to cut opposite side tooth faces of a blank, the latter tool being of different diameter from the first tool, by rotating the latter tool in engagement With a tapered gear blank while imparting a relative generating movement between the latter tool and blank as though the blank were meshing with a basic gear, represented by the latter tool.

32. The method of producing a pair of bevel gears which consists in cutting the side tooth faces of one member of the pair two sides simultaneously with a rotary annular face mill. having cutting edges of circular arc profile which are adapted to cut opposite side tooth faces of a blank, by rotating said tool in engagement with a tapered gear blank While imparting a relative generating movement between the tool and blank as though the blank were rolling with a basic gear, represented by the tool, whose axis intersects the blank axis in its apex, and in cutting the side tooth faces of the other member of the pair two sides simultaneously with a rotary annular face mill whose diameter is different from the diameter of the first tool, the latter tool having cutting edges of circular arc profile which are adapted to finish cut opposite side tooth faces of a blank, by rotating the latter tool in engagement with a tapered gear blank while imparting a relative generating move ment between the latter tool and blank as though the blank were meshing with a basic gear, represented by the latter tool, whose axis is offset from the axis of the blank.

ERNEST VVILDHABER. 

